Genetics are vital for understanding the evolution and domestication of horses and cattle. In recent years, genetic studies have helped to clarify where, when and how many times cattle and horses have been domesticated, which genes were involved, in the case of the horse and even resolved aspects of the phenotype of the extinct European wild horses. Genetics are also very important for breeding and thus for “breeding-back”. But a lot more research could be done to properly understand the aurochs, wild horse and their domestication. Often on my blog I am forced to engage in wild speculations because the genetic framework of the topic I am writing about has not been done yet. With this post, I want to give some impulses for genetic research not done yet that would be very useful for the topic of “breeding-back”, the aurochs and European wild horses.
- Resolving more coat colour loci and alleles in cattle. Many of the colour alleles in cattle are hypothetical, because the genetics of cattle colours are not as well-resolved as in dogs or horses for example. Thus, a rigorous study resolving many of the common cattle coat colour alleles would be fine, f.e. one that resolves the allele that is responsible for the recessive lack of red pigment in Podolian cattle, Tudanca, Grauvieh and Chianina, or the allele(s) that remove the rest of the pigments in the hair of Chianina. Resolving these recessive alleles and developing tests for those alleles would greatly help to remove them from “breeding-back” populations.
- after that, testing the colour alleles in aurochs DNA samples. Studies have been done that resolved the colour genotypes of predomestic wild horses, which also revealed some surprises (f.e. that the leopard spotted complex was found in wild horses). It would be awesome if the same would be done with DNA samples from the aurochs. It could reveal surprises too.
- Researching how many loci were affected in the domestication of the aurochs. That’s surely not an easy task, but it would be very interesting to know on how many loci aurochs and cattle differed, and if there are differences among cattle breeds. Some cattle breeds might differ from the aurochs on fewer loci than others.
- Finding some key genes that had a role in the domestication of the aurochs and resolving the alleles. This has been done for horses in a recent study, it found two genes that probably had a key role in the domestication of the horse. The same could be done with cattle and aurochs. This would also be helpful for recreating the aurochs or at least creating an aurochs-like animal with the CRISPR-Cas9 method.
- Studying the genetic background of the sexual dichromatism in Bos primigenius. It would be very interesting to know which loci and which genetic mechanisms are responsible for the sexual dichromatism seen in aurochs and cattle. Identifying individual alleles that are responsible for the well-marked dichromatism seen in the aurochs would also help to select for this trait in “breeding-back” cattle.
- Resolving some genes involved in horn size and curvature. Currently, only two loci involved in the production of bovine horns are identified, the Polled locus and the Scurred locus. They only determine if the individual is polled or not and if the horns are scurred or not. But the genes involved in horn size and curvature are not studied. Horn size is likely a quantitative trait, but maybe there are one or a couple of loci that have a particularly large impact on horn size. Curvature is probably polygenic as well. If some loci involved in those two traits are resolved, the alleles found in the British aurochs of which the genome has been resolved in 2015 could be checked and traced down in living cattle, what would making selecting for aurochs-like horns much easier than it currently is.
- Examining the Y chromosome of the Konik pony. So far, only the mitochondrial genome of the Konik pony has been examined. As domestic horses have a very limited Y chromosome diversity, finding unique haplotypes would be a strong hint for recent wild horse introgression, which would be the case if the Konik myth would be true. This, however, is very unlikely and it would be very nice to have it confirmed that also on the Y chromosome the Konik is a usual, robust domestic horse and not a surviving wild horse or a recent wild horse descendant.
- Resolving haplotypes in predomestic European wild horses and trying to trace them down in domestic horses. This would help to clarify how much wild horse introgression into the domestic horse gene pool there was in Europe, and also which breeds might have more influence from native European wild horses than others.
- Testing European wild horses for the dun allele. So far, the dun locus was tested only for two Siberian wild or ancient horses, which is a way too small sample size to tell us about the frequency of the respective alleles. Also, the locus was not examined in European wild horses, so that we do not know with certainty if they were black or black dun.